Drivers, pedestrians and bicyclists who use West Seattle’s lower swing bridge must find some other path for nine days, while city contractors move the span’s control tower cables.
The scheduled blockage, which is one phase of a multiyear renovation program, begins at 6 a.m. Saturday, April 20, and ends at 5 a.m. Monday, April 29. Both motor-vehicle lanes and the walk-bike trail will be closed.
The swing bridge, built in 1991, is a major truck route which provides the main access to container ship Terminal 5 west of the waterway, along with local industries and warehouses. So drivers can expect detouring semis on the high-rise bridge.
Historically, about 10,000 vehicles cross the low bridge per day, plus a few hundred people walking and bicycling, who can total 1,000 on warm days. It was a lifeline during the recent 2½-year repair closure of the seven-lane high-rise bridge, which reopened September 2022. Current volumes are still in flux and change drastically based on whether ships are docked on the Duwamish.
The low bridge is structurally sound but moving parts and underwater footings need extensive modernization, which the city has known and planned for years. In addition, the Seattle Department of Transportation took a harder look during the high-bridge closure, then found and repaired early-stage cracks in the low bridge girders, using epoxy and carbon wrap.
During the shutdown, free rides are offered on the West Seattle Water Taxi and King County Metro Transit buses crossing the river. These are funded by a voter-approved 2020 city sales-tax increase that’s available for a variety of transit purposes. To claim free trips, download Metro’s Transit Go app, find the “Rewards” section and enter LOWBRIDGE24.
Workers will relocate the drawspan control wires — which were mounted more than 30 years ago inside the West Seattle high-rise bridge‘s hollow girders — into a conduit below the Duwamish Waterway, while replacing switches, communications lines and the circuitry that guides the motion of drawspans, a $5 million effort in total.
The old network contains parts that are no longer available, and moving the cables underground eliminates the chance any future work on the high bridge might hinder low-bridge operations, said SDOT spokesperson Ethan Bergerson.
Last year, SDOT replaced the swing bridge’s two massive hydraulic cylinders, which each lift half the drawspan, so they can rotate, allowing ship passage.
Meanwhile, construction is underway on West Marginal Way Southwest, another common detour path. Trucks and general traffic converge upon a five-way intersection, at the western low-bridge approach.
Contractors are removing driveways, allowing for a “quiet zone” that requires less blasting of train horns in grade crossings. Walkways are also being added, apart from the rails. One northbound lane of Marginal has been blocked for months, making a complex area even trickier.
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